#ifndef __JetParser_h__
#define __JetParser_h__

#include "JetAST.h"
#include <string>
#include <map>
#include <utility>

namespace jetc {

   // Standalone parser for a subset of the JET template grammar. Mirrors the
   // character-level grammar implemented by JetCore's Tag::parseContainer /
   // Tag::Tag (attribute scanning, same-tag-name nesting depth, the <if>
   // <else> split) closely enough for well-formed templates, but is a fresh
   // implementation - it does not reuse JetCore's Tag classes, since those
   // fuse parsing and execution together (a real parse/execute split there
   // is a separate, larger refactor). Anything outside the modeled subset
   // (set/if/for/while/$[...]/literal text) is captured as an exact raw
   // source span and left for the existing interpreter (Tag::interpretSpan)
   // to run at compiled-program runtime, so unsupported constructs degrade
   // gracefully instead of failing to compile.
   class Parser {
    public:
      // topLevel is false for any nested sub-parse (an <if>/<for>/<while>
      // body, via parseSub) and true for the file's own top-level flow and
      // for anything spliced in from an <include> (which inherits the
      // includer's own topLevel, since it's meant to read as if written
      // inline at that point - see parseInclude). Only used to decide
      // whether a <tag name="X"> definition is eligible for compilation
      // (see parseTagDef) - one found at topLevel==false (nested inside
      // another construct) stays FALLBACK, unchanged, matching __tag.cpp's
      // own locally-scoped-registration semantics that only a true
      // top-level definition is guaranteed to always be registered by the
      // time any invocation could reach it.
      explicit Parser(const std::string &src, std::string baseDir = "", int includeDepth = 0, bool topLevel = true)
        : s(src), pos(0), baseDir(baseDir), includeDepth(includeDepth), topLevel(topLevel) {}

      std::vector<NodePtr> parseNodes();

    private:
      std::string s;
      size_t pos;
      size_t nextId = 0;
      std::string baseDir;
      int includeDepth;
      bool topLevel;

      bool eof() const { return pos >= s.size(); }
      bool starts(const std::string &lit) const;
      static bool isNameChar(char c);
      void skipWs();
      std::string readName();
      std::string peekTagName(size_t at) const;

      bool matchTagOpen(const std::string &name, size_t at) const;
      bool matchTagClose(const std::string &name, size_t at) const;

      // p points at '<' of some tag's opening; advances p past its '>' or
      // "/>", skipping quoted attribute values. Returns true if self-closing.
      bool skipOpenTag(size_t &p);
      void skipQuotedValue(size_t &p);
      void skipEmbeddedTag(size_t &p);

      std::map<std::string, std::string> parseAttrs(bool &hasContainer);

      // Scans forward from bodyStart (just after the opening tag's '>') for
      // tagName's matching close, tracking same-tag-name nesting depth and
      // (if lookForElse) a depth==1 "<else>" split point.
      // Returns {closePos, elsePos} (elsePos == npos if not found/not sought).
      std::pair<size_t, size_t> scanBody(size_t bodyStart, const std::string &tagName, bool lookForElse);

      std::vector<NodePtr> parseSub(size_t start, size_t end);

      // <include file="..."> is spliced in at compile time - read the
      // referenced file (resolved relative to baseDir) and parse ITS
      // content as if it had been written inline here, so everything in
      // it (custom <tag> definitions included) goes through this real
      // compiler, not the separate runtime interpreter (which has its own,
      // independently-buggy nested-tag handling). Returns the parsed nodes
      // to be spliced into the caller's own node list.
      std::vector<NodePtr> parseInclude();

      NodePtr parseVar();
      NodePtr parseSet();
      NodePtr parseIf();
      NodePtr parseFor();
      NodePtr parseWhile();
      NodePtr parseFallback();

      // <tag name="X">...</tag> at true top level (see topLevel above) -
      // compiles the definition body with a nested (topLevel=false) parse
      // instead of falling back to raw text, so jetc can generate a real
      // render function for it (see JetCodegen). Falls back to an ordinary
      // FALLBACK node (same as today) if the definition has no container
      // or no literal name= - degrades gracefully rather than failing to
      // compile.
      NodePtr parseTagDef();

      // <container> (any case/attributes/closing style, always void - see
      // isVoidTag) - a leaf node; the actual rendering logic lives in
      // Tag::renderContainer, called from generated code exactly as the
      // interpreter's own <container> dispatch calls it today.
      NodePtr parseContainerSlot();

      std::string newId(const std::string &prefix) { return prefix + std::to_string(nextId++) + "_"; }
   };

}

#endif